In March 1935 he passed his naval exams in gunnery and navigation, which would
have entitled him to become a lieutenant in the Royal Navy if he gave up
his Spanish nationality. This, however, he refused to do.

Just before the birth of the Infante Juan Carlos, the Count of
Barcelona decided to go hunting, with the doctor telling him and
his wife that the future king would not be born for weeks. When he
was told of the birth he drove to the hospital so quickly that he
broke an axle spring.

Pretender to the throne

Juan became heir to the Spanish throne after the renunciations
of his two older brothers, Alfonso and Jaime, both in 1933. To
assert his claim to the throne, he used the title of Count of Barcelona, a sovereign title
associated with the Spanish crown.

In 1936, his father sent him to enter Spain and participate in
the uprising but, near the French border, General Mola arrested him and
sent him back.

When General Francisco Franco declared Spain to be
a monarchy in 1947, he
characterised it as a reinstitution. However, Franco was afraid
that Don Juan would turn out to be too liberal and roll back the Falangist state. As a result,
in 1969 Franco passed over Juan, who would have been King if the
monarchy had continued uninterrupted, in favour of his son Juan
Carlos, who Franco believed would be more likely to continue the
Francoist State after his death. Juan Carlos surprised many by his support of
democratising Spain. However, Franco and the Count of Barcelona
did not have a good relationship, with the Count constantly
pressing Franco to restore the monarchy. Relations soured further
when Juan called Franco an "illegitimate usurper", while Franco
claimed he had a stronger claim to rule Spain than did Juan.

The Count of Barcelona formally renounced his rights to the
Crown eight years after being displaced as recognized heir to the
throne by Franco, and two years after his son Juan Carlos had
become King. In return, his son officially granted him the title of
Count of Barcelona, which he had claimed for so long.

He was buried as Juan III (John III of Spain),
with honours due a King, in the Royal Crypt of the monastery of San Lorenzo del Escorial, near Madrid. His wife survived him for
seven years.

The generations
indicate descent form Charles I, under
whom the crowns of Castile and Aragon were united, forming the
Kingdom of Spain. Previously, the title Infante had been largely
use in the different realms.